mechanisms before reactions: a mechanistic approach to the...

Mechanisms before Reactions: A Mechanistic Approach to theOrganic Chemistry Curriculum Based on Patterns of Electron FlowAlison B. Flynn* and William W. Ogilvie

Department of Chemistry, University of Ottawa, Ottawa, ON K1N 6N5, Canada

ABSTRACT: A significant redesign of the introductoryorganic chemistry curriculum at the authors’ institution isdescribed. There are two aspects that differ greatly from atypical functional group approach. First, organic reactionmechanisms and the electron-pushing formalism are taughtbefore students have learned a single reaction. Theconservation of electrons, atoms, and formal charges, howthe use of curved arrows helps describe the mechanism, and how to predict reaction mechanisms are emphasized. Second, thereactions taught in the first two semesters of organic chemistry are arranged by their governing mechanism, rather than byfunctional group. The reactions are taught in order of increasing difficulty, beginning with acid−base reactions, followed bysimple additions to π electrophiles, and ending the first semester with addition to π nucleophiles, including aromatic chemistry.The reactions in the second organic semester begin with elimination reactions, then substitutions, and finally more complex πnucleophile mechanisms (e.g., aldol reaction) and π electrophile reactions (e.g., acetals). Ultimately, the goal is for students tolearn and interpret reactions based on their patterns of reactivity, allowing them to analyze, predict, and explain new reactions. Inprinciple, a mechanistic method is more general, easier to understand, and provides a better way to achieve a deep understandingof chemical reactivity. Chemical reactions follow patterns, and these patterns can allow a chemist to predict how a chemical willbehave, even if they have never seen a particular reaction before. Visualizing reactivity as a collection of patterns in electronmovement is a more powerful and systematic way to approach learning in organic chemistry. It still requires some memorization,but because the course organization is directly linked to reaction patterns, deeper learning in the discipline is possible.

KEYWORDS: First-Year Undergraduate/General, Second-Year Undergraduate, Curriculum, Organic Chemistry,Problem Solving/Decision Making, Constructivism, Mechanisms of Reactions, Lewis Structures

■ INTRODUCTION

Organic chemistry has existed as a distinct science for less than200 years.1 In the beginning, chemical tests were used to detectthe presence of functional groups, ultimately to identifymolecular structures; reaction mechanisms were not yetknown. Because of the importance of these chemical tests, itwas natural that classroom instruction would also focus on thefunctional groups detected by the tests. This approach requiredextensive rote memorization without understanding. Deepunderstanding of the discipline required a long time andconsiderable experience to acquire.Kermack and Robinson first introduced use of the curved

arrow to depict bond-forming and bond-breaking processes in1922.2 This was the first method describing chemical reactivitythat considered the movement of electrons, rather than justatoms, when describing chemical reactions. This method hasproven to be a more general and powerful way to understandchemistry. Using this method, it is possible to describe why areaction occurred, to explain many concepts that had previouslybeen derived from empirical observations, and to predictreactivity.Today, most textbooks3,4 and courses emphasize mecha-

nisms but remain organized around the functional groupconcept, even though experts rely on reaction mechanisms andthe electron-pushing formalism (EPF) in their work.5 The

functional group organization frequently results in extensiverote memorization, does not always provide concurrentunderstanding, presents complex topics before simple conceptsare taught, and frequently confuses students by making thesubject appear random and difficult.6 Common reaction names(e.g., elimination and oxidation) often compound learningdifficulties, as they can give the impression of new reactiontypes or opposite reactivity (e.g., electrophilic and nucleophilicaddition).Research is showing that students can benefit from

mechanistic thinking.7−9 Despite the emphasis on the EPF,students tend to memorize reactions rather than using the EPFto work through organic reactions. For many students, the EFPis meaningless.10−12 Moreover, many students struggle withmechanistic tasks and seem to lack the predictive capacity thatshould arise from mechanistic competence.13,14 A number ofsuggestions have been published to help students learnmechanisms.15−17 Friesen suggested avoiding the overuse ofshort forms (e.g., R or Ph) and shortcuts (e.g., proton-transfersteps), and instead recommended (a) including key electronsand curved arrows, (b) using balanced reaction equations, and(c) distinguishing between ionic and covalent bonds (e.g.,showing Na+ and OH− rather than NaOH).15 When teaching

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© XXXX American Chemical Society andDivision of Chemical Education, Inc. A DOI: 10.1021/ed500284d

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mechanisms, students can work through learning activities andbe given immediate feedback.11,18,19

Improvements to introductory organic chemistry coursecurricula have been suggested.20−22 For example, Goldishsuggested a fundamental change in the organic curriculumincluding (a) focusing on the use of mechanisms, emphasizingelectron flow and electron pair donors and acceptors, (b) notstarting with radical reactions, since most reactions taught areionic in nature, (c) leaving the confusing discussion of SN1 and

related reactions until later, and (d) covering carbonylchemistry fairly early.23

Herein, the fundamental changes to the organic curriculumto a mechanistic approach are described. The goal is to helpimprove student learning and students’ abilities to solve newproblems. In this approach: (1) the concept of a mechanismand the electron-pushing formalism is taught before studentslearn a single reaction, (2) reactions are organized by thepattern of their governing mechanism, and (3) early sections of

Table 1. Curriculum Overview for the First Two Organic Chemistry Coursesa

aOnly the key components of each mechanism are shown in the table. In the course, the full mechanisms (including each proton transfer) are drawnby students and professor.

Journal of Chemical Education Article

DOI: 10.1021/ed500284dJ. Chem. Educ. XXXX, XXX, XXX−XXX

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an organic chemistry course are structured so that students gainskills needed to interpret, explain, and predict mechanisms.This new curriculum was first implemented in January 2012(Organic Chemistry I), and the early results have been veryencouraging.

■ OVERALL STRUCTURE OF COURSESThe organic chemistry sequence at the University of Ottawa isdivided into four semester-long courses. The first two organicchemistry courses are structured as follows:

• Organic Chemistry I is a one-semester, first-year course(CHM 1321/1721) taught in the winter (4 Englishsections, 1 or 2 French sections)

• Organic Chemistry II is a one-semester, second-yearcourse (CHM 2120/2520) taught in the summer and fall(3 English sections, 1 French section)

These two courses encompass the same material taught inmost second-year, two-semester courses. They are large-enrollment courses with more than 1000 students per coursedivided into sections of 200−420 students. The third andfourth organic chemistry courses are a continuation of thesecond, but they have not been the main focus of thecurriculum change and so are not described in detail here. Anoverview of the new courses’ structure is in Table 1, along withan approximate timing of the sections.Sections 1−4: Organic Structure

The course begins with a section on drawing Lewis structures,line structures, formal charge, and molecular orbital theory (σ,σ*, π, and π*).24 Line structures are used extensively in thecourse because they reduce “clutter” in structural drawing anddraw focus to the functional groups. For the same reason, the“R” notation (e.g., see Table 1) is avoided. Although resonanceis traditionally taught in conjunction with Lewis structures, itcan be a difficult concept to grasp and use without the benefitof electron pushing. Thus, all electron movement, includingresonance, is delayed to the first mechanism section of thecourse (section 5).After sections 2−4 on the physical properties of organic

compounds, conformational analysis, and stereochemicalanalysis, the part of the course on reactivity begins. Thereactions learned in the rest of the course (sections 6−16)incorporate concepts from the earlier parts of the course.Section 5: Reaction Mechanisms and the Electron PushingFormalism

The first section in the reactivity portion of the course (section5) focuses on the concepts of mechanisms and the EPF. Thissection is taught before students learn a single reaction.Students need to learn to think mechanistically and use curvedarrows before adding the complexity of reactions and beforethey start trying to memorize mechanisms in an unconnectedway. The focus is on three learning outcomes (LOs) thatstudents will achieve by the end of this section (Box 1); theywill be able to (1) draw the products of a reaction, given thestarting materials and curved arrows, (2) add curved arrows,given the starting materials and products, and (3) draw thecurved arrows and predict the products of a new reaction, giventhe starting materials.When drawing curved arrows, the arrows must start from

electrons and point to an atom or bond. In the first twoorganic courses, arrows are not drawn between chargesbecause electrons and atoms (not charges) form bonds. The

purpose of this section is not for students to memorize themechanisms; rather, the goal is to achieve the above learningoutcomes. On midterms and exams, the questions associatedwith these learning outcomes include reactions that studentshave not yet seen (e.g., Box 1d).Simple resonance structures (Box 1a, c, e) are taught first, so

that students need only focus on moving electrons, not bothelectrons and atoms as they must do in reactions. The principlethat electron-rich (negative or δ−) and electron-deficient(positive or δ+) centers attract is emphasized.In class, mechanisms are color-coded so that students can see

how and where specific electrons have moved (e.g., nucleophilein blue, electrophile in green, curved arrows in red (Table 1)).Drawing all of the lone pairs of electrons and atoms near thereacting center helps in the calculation of formal charges andreinforces the need to keep track of all electrons and atoms.Students can answer resonance and mechanism questions inclass using a classroom response system (CRS).18,25,26

Next, the mechanism learning outcomes are addressed usingorganic reactionsthis is still before students have learned asingle reaction (Box 1b,d,f). Now, students must track/conserve atoms as well as charges and electrons. Drawing allthe nonbonding electrons, the implicit hydrogen atoms, andlabeling (e.g., numbering) the atoms at or near the reactingcenters are emphasized.In assignment questions, students are asked questions related

to the aforementioned learning outcomes, as well as questionsthat address common errors (e.g., Box 2). The focus inquestion 1 is to keep track of electrons. In question 2, studentsare asked to add the appropriate formal charges to theproducts.27

Students are quite successful in this section of the course.They have the opportunity to develop basic EPF skills beforeadding the complexities that accompany chemical reactions. For



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example, the two questions shown in Box 3 were given on amidterm exam before students had learned a single reaction;90% of students answered question 1 correctly and 79%answered question 2 correctly (N=354).

Section 6: Brønsted Acid−Base Chemistry

The first organic reaction taught is the proton transfer (section6). Brønsted acid−base chemistry serves as an introduction tochemical reactions, including the principles of equilibrium andmicroscopic reversibility.The mechanism learning outcomes (Box 1) are revisited as

they apply to acid−base chemistry, and students are expected toshow every proton transfer explicitly using the EPF. That is,students may not use the −H+/+H+ or PT (proton-transfer)conventions20 or skip proton-transfer steps in any mechanismtaught in the first two semesters of organic chemistry. Studentsare still learning to keep track of electrons and atoms at thispoint and even a proton transfer can lead to avoidable errors.

■ REORGANIZATION OF THE REACTIONS IN THENEW CURRICULUM: SECTIONS 7−16

The next sections (Table 1, sections 7−16) of the course differmost from the functional group approach. The reactions aregrouped by similar mechanisms and taught with a gradient ofdifficulty. All of the reactions taught over two courses can begrouped into four categories: acid−base, π electrophiles, π

nucleophiles, and σ electrophiles. The patterns and similaritiesbetween mechanisms are emphasized instead of memorizationto promote improved student mastery of the concepts in thecourse so they can learn new mechanisms independently.SN1, SN2, E1, and E2 reactions have been moved to the

second semester course. Although these reactions usually makesimple products and have traditionally been taught first (afteracid−base), the reactions have very complex rules of reactivity.They require an understanding of leaving group abilities,nucleophile and base strengths, analyzing the degree ofsubstitution of the α-carbon (the carbon that bears the leavinggroup), solvent effects, and more. Students must also considercompeting reaction pathways, regiochemistry, and stereo-chemistry, all when they have only just learned a protontransfer. Teaching those reactions so early forces students tolearn a great deal of information in a very short time, and, as aresult, many students resort to memorization. Instead, thosereactions are taught after students have acquired a strongermechanistic base.Section 7: π Electrophiles

After acid−base chemistry, addition reactions to π electrophilesthat do not bear a leaving group are taught. The reactions insection 7 involve the addition of nucleophiles to aldehydes,ketones, and imines (Figure 1) under acidic or basic conditions.

The main step of the mechanism is the same in all thesereactions (Figure 1, gray box); only the order of protonationand deprotonation changes. The key step involves only thereaction between the nucleophilic atom with the electrophiliccarbonyl carbon and has the “leaving group” (the π bond)pulled toward the more electronegative atom. Acid activates theelectrophile (by “pulling” on the π electrons), while baseactivates or generates a nucleophile (an electron “push”). Thefundamental mechanistic pattern is the same (shown in redarrows) regardless of whether the reaction proceeds underacidic or basic conditions. Students only need to consider onepattern of electron movement, rather than memorize tworeactions (acid and base catalyzed). By teaching these reactionstogether, the concepts of acid and base catalysis are introducedin a simple way. The role of the catalyst activatingnucleophile or electrophileis a pattern that is consistentthroughout organic chemistry. Teaching students why a catalystworks the way it does (e.g., acid activates electrophiles, baseactivates nucleophiles) provides them with a foundation toquickly understand reactions they have not seen before.The specific reactions taught include the Grignard reaction,

organolithium reactions, reduction with NaBH4 (aldehydes and

Figure 1. Reactions of nucleophiles with π electrophiles that do notbear a leaving group.



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ketones) and NaBH3CN (imines). The electrophiles includealdehydes, ketones, and imines. Those electrophiles do not bearan obvious leaving group (e.g., as does an acid chloride) andthe reaction stops at the stage of the tetrahedral intermediate(with the types of nucleophiles that are included at this stage).Reactions to form hydrates and hemiacetals (especiallyintramolecular variants) are also taught at this stage, becausethey proceed by the same key steps (Figure 1). Stereo-chemistry, conformational analysis, and molecular orbitalconcepts are connected to these reactions.28

Sections 8−9: π Nucleophiles

In section 8, the reactions of π-bond nucleophiles are analyzedas they react with a variety of electrophiles by similar patternsof electron flow (Figure 2). Closely related mechanisms aretaught, including the reactions of alkenes with HX (section 8a),X2 (section 8b), or peroxy acids (section 8c). Stereochemicaland regiochemical considerations are addressed, as are theconcepts of nucleophilic solvents and intramolecular reactions.When discussing relative carbocation stability, the concept ofhyperconjugation and the Hammond postulate are included.Enol ethers are included in the Markovnikov section,reinforcing the role of resonance in reactivity. With eachreaction variant, including alkynyl nucleophiles, the repeatingpatterns of, and the reasons for, reactivity in controllingregiochemistry (Markovnikov addition of nucleophiles) areemphasized. The roles of orbitals in controlling stereochemicaloutcomes are also discussed.Two reactions that give anti-Markovnikov addition of

nucleophiles are also taught here: hydroboration−oxidation ofalkenes and radical-promoted addition of HX to alkenes(including single-headed arrows). Other radical reactions, suchas the sodium/ammonia reduction of alkynes, are not taught inthe first two semesters but, instead, are taught in the radicalsections of more senior courses.Section 9 includes aromaticity, antiaromaticity, and the

reactions of benzene derivatives with activated electrophiles.The electron flow pattern of benzene when it reacts withelectrophiles is identical to the first step of reactions of alkeneswith electrophiles (Figure 2). The second (deprotonation) stepis readily explained by the regeneration of aromaticity drivingthe reaction; students have already learned the acid−base steprequired. Nitration, sulfonation, aromatic halogenation, Frie-del−Crafts alkylation, and acylation reactions are typicallytaught.To explain the effects of directing groups, links are made to

inductive effects (sections 1 and 6), resonance (section 5),hyperconjugation (section 8), and the Hammond postulate(section 8). Synthesis is taught from the very first reaction in

section 7. The section on aromaticity in particular provides anopportunity for students to design syntheses in which the orderof reactions affects the product isomer.29,30 In all of thereactions in Figure 2, the pattern of electron movement is thesame in the key step. The curved arrows can be followed ineach one to draw the resulting product/intermediate, analyzethe intermediate(s), and to deduce what happens next.

Sections 10−11: E1, E2, SN1, and SN2

The second course in organic chemistry (Organic ChemistryII) begins, after a brief review, with elimination reactions,specifically E1, E2, and oxidations of alcohols and aldehydes(Table 1, section 10). Students have already learned the E1mechanism, in part, with the analysis of carbocations in section8 and the E1-type elimination step in the electrophilic aromaticsubstitution reactions (section 9). Beginning the second coursewith the E1 reaction provides a link between the two courses.Students must consider electrophilic structure (e.g., degree ofsubstitution of the α-carbon), leaving group ability, solventeffects, regiochemistry, and stereochemistry. The E2 reaction istaught next, linking back to the acid−base section of the firstcourse. Oxidation reactions are taught with E2 because theelectron flow patterns of key steps are identical (Figure 3).

With the SN1 and SN2 reactions come the analysis of productratios and how to predict which of the four reactions, E1, E2,SN1, or SN2, will predominate with given substrates andreaction conditions. The molecular orbitals that dictate thecourse of these reactions (especially stereochemical aspects) arealso analyzed.Section 13: Enols and Enolates as π Nucleophiles

After section 12 on spectroscopy, nuclear magnetic resonance31

and infrared, enols and enolates are the π nucleophiles in thenext mechanism (Figure 2). In section 13, sections 8 and 9 (πnucleophiles) are revisited, with some additional complexity inthe generation of the π bond (the enol/enolate). The

Figure 2. Examples of reactions that fit the category of π nucleophiles. The extra mechanism proceeds by the same electron flow pattern and is usedto oxidize thiols, such as the ones found in skunk spray.

Figure 3. Parallel between the E2 and alcohol oxidation reactionmechanisms.



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electrophilic partners have been seen before, i.e., X2, alkylhalides, and carbonyls, although this is the first time studentslearn of a π bond reacting with a carbonyl, providing anopportunity to connect earlier concepts. These reactions arealso revisited after sections 14−16 (section 13 has also beentaught after sections 14−16).Sections 14−16: π Electrophiles That Bear a Leaving Group

Sections 14−16 involve π electrophiles that bear a leavinggroup (Figure 4). Section 14 is the chemistry of carboxylic acidderivatives, which proceeds by two main mechanisms, eitherunder basic or acidic conditions. Students learn the relativereactivity of various electrophiles based on their leaving groupability. They also determine whether these reactions should beconducted under acidic or basic conditions, depending on thereacting partners and desired product.Section 15 involves the chemistry of acetals and derivatives,

which proceeds by the same mechanistic pattern as thederivatives of carboxylic acids, although the leaving group is notapparent until the tetrahedral intermediate forms. Nucleophilicaromatic substitution (section 16) proceeds by the samemechanistic pattern as the two above, although on a benzenering instead of a carbonyl. The pattern of the mechanismdictates the organization of this curriculum, not the functionalgroup involved.Students are explicitly shown, and are asked to find, the

parallels between the acid- and base-catalyzed mechanisms,which have the same key steps and differ only in the protontransfer steps. Students are taught how to determine whetherthe reaction will stop after the collapse of the first tetrahedralintermediate or whether a second addition of a nucleophile willoccur (dashed curved arrows in Figure 4), depending on thereacting partners. When situations arise in which multiplereaction pathways are possible, the various mechanisticpathways are analyzed in class and students learn to predictthe correct products. For example, some decisions related tothe site of deprotonation can be made on the basis of pKa.Students must show every step of a mechanism without takingshortcuts15 as is done by the instructors when modelingworking through mechanisms.

■ IMPLEMENTING THIS APPROACH

This new curriculum was first implemented in January 2012with Organic Chemistry I and it has been used ever since. Allprofessors who teach these courses, as well as professors of thethird-year organic chemistry courses, decided to move forward

with the new curriculum to ensure continuity between eachyear of instruction.The instructors found the conversion to the new curriculum

to be straightforward. At the simplest level (from aninstructional input point of view), the new curriculum requiredonly rearranging sections of the course and modifying somesynthesis questions. The associated laboratory experimentswere rearranged to stay aligned with the order of the coursecontent. Professors rearrange sections within a course if theywish, and students can still be directed to the relevant sectionsin a functional group textbook. Continuing discussions help torefine and improve the teaching and learning in the courses.Additionally, students’ feedback about the course structure hasbeen very positive.

■ NEXT STEPS

On the basis of the encouraging experiences with this firstchange in the curriculum, further changes are being consideredby moving all carbonyl chemistry into first year, which allows allrelated reactions to be taught together, keeps complexstereochemical considerations to a minimum in the first course,and helps make connections to biochemical processes earlier. Inaddition to acetals, the synthesis of simple heterocycles will beintroduced, which form by a combination of acetal and enol-type mechanisms. Radical reactions will be omitted from thefirst two years, so that the focus can be on ionic reactionsexclusively.The second semester will start with aromatic nucleophiles,

followed by the π nucleophiles (alkenes and alkynes); theformer has fewer reaction variants and can be taught with aminimum of stereochemistry. Next will be eliminationreactions, the reverse of addition to alkenes, hence revisitingthe principle of microscopic reversibility (first learned withacid−base chemistry). After that comes substitution reactionsand identifying reaction conditions that will favor one reaction(E1, E2, SN1, SN2) over another. The second semester willfinish with π nucleophiles: enols and enolates. The reaction ofthose nucleophiles with carbonyls will provide a link back to thefirst semester course and into the third organic course. Thethird year course deals with advanced enolate chemistry, suchas the Evans aldol reaction.32 In that course, pericyclic andcycloaddition reactions, rearrangements, advanced heterocyclicchemistry, radical reactions, and cross-coupling reactions arealso taught.

Figure 4. Section: (14) π electrophiles bearing a LG; (15) π electrophiles bearing a nonobvious LG and acid-catalyzed conditions; (16) aromatic (π)electrophiles bearing a LG. Only key steps are shown (not proton transfers).



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■ CONCLUSIONSThe standard organic curriculum for the first two semesters oforganic chemistry was modified in two major ways. First, asection dedicated purely to the electron-pushing formalism andthe principles of reaction mechanisms was added to the first-semester course. This section is taught before students havelearned a single reaction. The goal is to enable students tomaster the mechanism learning outcomes without thecomplexity of later reactions and, importantly, withoutmemorizing the processes and simply decorating with arrows.Assessment is aligned with those intended learning outcomes(LOs) by giving midterm and exam questions that address thethree key mechanism LOs, using reactions students have neverseen.Second, the portion of the courses dedicated to reactions was

redesigned. The reactions were arranged based on the patternof their governing mechanism, and the mechanisms were taughtin a gradient of difficulty by teaching the mechanistically mostsimple reactions first. The patterns in electron movement wereemphasized to promote a systematic approach to learningorganic chemistry. The goal is to improve students’ abilitiesusing the electron pushing formalism, including predicting andexplaining unknown reactions.In this report, the focus was only on the aspects of the

curriculum that related to teaching reactions and mechanisms,although there remain many other curricular and pedagogicalaspects included in course planning. Because of the earlyindicators of success (the ease of implementation, student andinstructor satisfaction in particular), a learning evaluation of thisnew curriculum will be conducted, which will be reported indue course.

■ AUTHOR INFORMATIONCorresponding Author

*E-mail: [email protected]

The authors declare no competing financial interest.

■ ACKNOWLEDGMENTSWe sincerely thank our colleagues who were willing to workwith us to refine and implement this innovative curriculum inall our organic chemistry courses.

■ DEDICATIONWe dedicate this article to Tony Durst and to the memory ofKeith Fagnou. Their insights into teaching and learning willalways influence our work.

■ REFERENCES(1) Giunta, C., Ed. Atoms in Chemistry: From Dalton’s Predecessors toComplex Atoms and Beyond; ACS Symposium Series; AmericanChemical Society: Washington, DC, 2010.(2) Kermack, W. O.; Robinson, R. An Explanation of the Property ofInduced Polarity of Atoms and an Interpretation of the Theory ofPartial Valencies on an Electronic Basis. J. Chem. Soc. 1922, 121, 427−440.(3) Klein, D. Organic Chemistry, 1st ed.; John Wiley & Sons, Inc.:Hoboken, NJ, 2012.(4) Karty, J. Organic Chemistry: Principles and Mechanisms; W. W.Norton & Company: New York, 2013.(5) Bhattacharyya, G. From Source to Sink: Mechanistic ReasoningUsing the Electron-Pushing Formalism. J. Chem. Educ. 2013, 90,1282−1289.

(6) Anderson, T. L.; Bodner, G. M. What Can We Do About’Parker’? A Case Study of a Good Student Who Didn’t ‘Get’ OrganicChemistry. Chem. Educ. Res. Pract. 2008, 9, 93−101.(7) Grove, N. P.; Cooper, M. M.; Cox, E. L. Does MechanisticThinking Improve Student Success in Organic Chemistry? J. Chem.Educ. 2012, 89, 850−853.(8) Anderson, J. P. Learning the Language of Organic Chemistry:How Do Students Develop Reaction Mechanism Problem-SolvingSkills. Ph.D. Dissertation, Purdue University: West Lafayette, IN,2009; http://docs.lib.purdue.edu/dissertations/AAI3379296/ (ac-cessed Jan 2015).(9) Straumanis, A. R.; Ruder, S. M. New Bouncing Curved ArrowTechnique for the Depiction of Organic Mechanisms. J. Chem. Educ.2009, 86, 1389−1391.(10) Ferguson, R.; Bodner, G. M. Making Sense of the Arrow-Pushing Formalism Among Chemistry Majors Enrolled in OrganicChemistry. Chem. Educ. Res. Pract. 2008, 9, 102−113.(11) Grove, N. P.; Cooper, M. M.; Rush, K. M. Decorating withArrows: Toward the Development of Representational Competence inOrganic Chemistry. J. Chem. Educ. 2012, 89, 844−849.(12) Bhattacharyya, G.; Bodner, G. M. It Gets Me to the Product”:How Students Propose Organic Mechanisms. J. Chem. Educ. 2005, 82,1402−1407.(13) Kraft, A.; Strickland, A. M.; Bhattacharyya, G. ReasonableReasoning: Multi-Variate Problem-Solving in Organic Chemistry.Chem. Educ. Res. Pract. 2010, 11, 281−292.(14) Bhattacharyya, G. Trials and Tribulations: Student Approachesand Difficulties with Proposing Mechanisms Using the Electron-Pushing Formalism. Chem. Educ. Res. Pract. 2014, 15, 594−609.(15) Friesen, J. B. Saying What You Mean: Teaching Mechanisms inOrganic Chemistry. J. Chem. Educ. 2008, 85, 1515−1518.(16) Wentland, S. H. A New Approach to Teaching OrganicChemical Mechanisms. J. Chem. Educ. 1994, 71, 3−8.(17) Penn, J. H.; Al-Shammari, A. G. Teaching Reaction MechanismsUsing the Curved Arrow Neglect (CAN) Method. J. Chem. Educ.2008, 85, 1291−1295.(18) Bryfczynski, S. P.; Brown, R.; Hester, J.; Herrmann, A.; Koch, D.L.; Cooper, M. M.; Grove, N. P. uRespond: iPad as Interactive,Personal Response System. J. Chem. Educ. 2014, 91, 357−363.(19) Connect; connect.mcgraw-hill.com (accessed Jan 2015).(20) Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry; OxfordUniversity Press: Oxford, 2012.(21) Advances in Teaching Organic Chemistry; Duffy-Matzner, J. L.,Pacheco, K. A. O., Eds.; American Chemical Society: Washington, DC,2012; Vol. 1108.(22) Reingold, I. D. Bioorganic First: a New Model for the CollegeChemistry Curriculum. J. Chem. Educ. 2001, 78, 869−871.(23) Goldish, D. M. Let’s Talk About the Organic Chemistry Course.J. Chem. Educ. 1988, 65, 603−604.(24) Cooper, M. M.; Grove, N.; Underwood, S. M.; Klymkowsky, M.W. Lost in Lewis Structures: An Investigation of Student Difficulties inDeveloping Representational Competence. J. Chem. Educ. 2010, 87,869−874.(25) Top Hat. https://tophat.com/ (accessed Jan 2015).(26) Straumanis, A. R.; Ruder, S. M. A Method for Writing Open-Ended Curved Arrow Notation Questions for Multiple-Choice Examsand Electronic-Response Systems. J. Chem. Educ. 2009, 86, 1392−1396.(27) Hennessy, J. Formal Charge. https://www.youtube.com/watch?v=9dH4VY1-WxI (accessed Jan 2015).(28) Fleming, I. Molecular Orbitals and Organic Chemical Reactions;John Wiley & Sons: Chichester, UK, 2010.(29) Flynn, A. B. Developing Problem-Solving Skills ThroughRetrosynthetic Analysis and Clickers in Organic Chemistry. J. Chem.Educ. 2011, 88, 1496−1500.(30) Flynn, A. B. How Do Students Solve Organic SynthesisLearning Activities? Chem. Educ. Res. Pract. 2014, 15, 747−762.(31) Flynn, A. B. NMR Interpretation: Getting from Spectrum toStructure. J. Chem. Educ. 2012, 89, 1210−1212.



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mailto:[email protected]

http://docs.lib.purdue.edu/dissertations/AAI3379296/

connect.mcgraw-hill.com

https://tophat.com/

https://www.youtube.com/watch?v=9dH4VY1-WxI

https://www.youtube.com/watch?v=9dH4VY1-WxI


(32) Kurti, L.; Czako, B. Strategic Applications of Named Reactions inOrganic Synthesis; Elsevier Academic Press: New York, 2005.



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